Addition Of Citric Acid Research Articles

Higher Extrusion Temperature Induces Greater Formation of Less Digestible Type V and Retrograded Starch in Iron-Fortified Rice Grains But Does Not Affect Iron Bioavailability: Stable Isotope Studies in Young Women

BackgroundHot extrusion is widely used to produce iron-fortified rice, but heating may increase resistant starch and thereby decrease iron bioavailability. Cold-extruded iron-fortified rice may have higher bioavailability but has higher iron losses during cooking. Thus, warm extrusion could have nutritional benefits, but this has not been tested. Whether the addition of citric acid (CA) and trisodium citrate (TSC) counteracts any detrimental effect of high-extrusion temperature on iron bioavailability is unclear. ObjectivesOur aim was to assess the effects of varying processing temperatures on the starch microstructure of extruded iron-fortified rice and resulting iron solubility and iron bioavailability. MethodsWe produced extruded iron-fortified rice grains at cold, warm, and hot temperatures (40°C, 70°C, and 90°C), with and without CA/TSC at a molar ratio of iron to CA/TSC of 1:0.3:5.5. We characterized starch microstructure using small- and wide-angle X-ray scattering and differential scanning calorimetry, assessed color over 6 mo, and measured in vitro iron solubility. In standardized rice and vegetable test meals consumed by young women (n = 22; mean age: 23 y; geometric mean plasma ferritin: 29.3 μg/L), we measured iron absorption from the fortified rice grains intrinsically labeled with 57ferric pyrophosphate (57FePP), compared with ferrous sulfate (58FeSO4) solution added extrinsically to the meals. ResultsWarm and hot extrusion altered starch morphology from native type A to type V and increased retrograded starch. However, extrusion temperature did not significantly affect iron solubility or iron bioavailability. The geometric mean fractional iron absorption of iron from fortified rice extruded with CA/TSC (8.2%; 95% CI: 7.9%, 11.0%) was more than twice that from extruded rice without CA/TSC (3.0%; 95% CI: 2.7%, 3.4%; P < 0.001). ConclusionsHigher extrusion temperatures did not affect iron bioavailability from extruded rice in young women, but co-extrusion of CA/TSC with FePP sharply increased iron absorption independently from extrusion temperature. This trial is registered at www.clinicaltrials.gov as NCT03703726.

Insights into the enhanced fluoranthene degradation in citric acid coupled Fe(II)-activated sodium persulfate system

Abstract Polycyclic aromatic hydrocarbons (PAHs), which are present in contaminated groundwater, have attracted increasing attention because of their serious harm to humans. In this study, the degradation performance of fluoranthene (FLT), a typical tetracyclic PAHs in organic contaminated sites, was investigated in the persulfate (PS)/Fe(II)/citric acid (CA) system. The effects of PS, CA, and Fe(II) doses on FLT degradation were tested. With the molar ratio at 60/20/5/1 of PS/Fe(II)/CA/FLT, FLT removal reached 96.3% in 120 min, much higher than 62% removal without CA at the same PS and Fe(II) doses, indicating that the addition of CA could remarkably enhance the FLT degradation. The water quality conditions (pH, anions and humic acid) were also investigated for their effects on FLT degradation. The results of probe tests, electron paramagnetic resonance detection and scavenging experiments showed that and acted predominantly on FLT degradation. The influence of surfactants on FLT degradation was examined. Furthermore, the primary degradation intermediates of FLT were detected by GC-MS and the possible degradation pathways of FLT were proposed. Finally, the effectiveness of the PS/Fe(II)/CA process for the FLT degradation in actual groundwater demonstrated that the process has a great prospect for the remediation of FLT-contaminated groundwater.

Pengaruh Penambahan Jeruk Nipis Terhadap Ph, Total Antosianin Dan Aktivitas Antioksidan Pada Minuman Bunga Telang

Blue pea flower has many benefits, one of which contains anthocyanins which function as antioxidants and pigments. The weakness of the use of blue pea flower on anthocyanin pigments is less stable. Anthocyanins are more stable in acidic solutions than in basic solutions. The addition of lime which is rich in citric acid is expected to increase the acidity of the pH of the blue pea flower (pH 5) because lime has a pH of 2.48-2.5. This study aims to determine the effect of adding lime to the characteristics of the blue pea flower drink and to determine the appropriate addition of lime to produce a blue pea flower drink with the best characteristics. The research method used a Completely Randomized Design (CRD) experimental design with lime addition treatment consisting of 6 levels, namely: 0%, 1%, 2%, 3%, 4%, 5%. The data obtained were analyzed by means of variance and if the treatment had an effect on the observed variables, it was continued with the Duncan Multiple Range Test. The results showed that the addition of lime had a very significant effect (P&lt;0.01) on pH, vitamin C levels, total anthocyanins and antioxidant activity. The addition of 5% lime is the best result in producing blue pea flower drink, with the characteristics of pH 4.81, vitamin C content of 5.47%, total anthocyanin 2.19 mg/g and antioxidant activity of 45.60%. The addition of citric acid has the potential to increase the stability of anthocyanins and antioxidants in blue pea flower drink by decreasing pH, increasing total anthocyanins, increasing vitamin C and increasing antioxidant activity.&#x0D; &#x0D; Keywords: blue pea flower, lime, antioxidant activity, anthocyanin stability

A simple preparation of low water-soluble crosslinking starch-based foam containing palm oil: Thermo-physicochemical properties

A simple preparation method was established for a low water-soluble citric acid crosslinking starch-based foam containing palm oil. The method was performed by pouring the boiling citric acid solution into the starch compound unlike the citric acid starch crosslinking by conventional solution casting. Thermo-physicochemical properties of the starch-based foams were examined. The I3300/I1149 intensity ratio of non-citric acid-containing foam was higher, suggesting greater amounts of the available -OH groups. The addition of citric acid into the starch matrix exhibited weaker thermal stability that was attributed to the lower thermal stability of the substituted ester bonds. The increment of citric acid concentration increased thermoplastic starch foams densities as well as their cell wall thickness. No differences in moisture absorption behavior were observed after soaking in water, the non-citric acid-filled foam exhibited dissolution and changed from its original shape upon drying. Experimental results showed a promising alternative methodology to prepare low water-soluble citric acid crosslinked starch-based foam to replace conventional solution casting.

Lignin Pellets for Advanced Thermochemical Process—From a Single Pellet System to a Laboratory-Scale Pellet Mill

Lignin pellets were produced using a single pellet system as well as a laboratory-scale pellet mill. The feedstock used in this work was lignin isolated from poplar wood (Populus tremuloides) using a direct saccharification process. An investigation was performed on the influence of the initial moisture content on the dimensions, impact and water resistance, fines content, mechanical durability, calorific value, and ash content, and, finally, the ultimate analysis was performed. These properties were then compared to pellets made from softwood bark using the same pelletization unit. Lignin pellets were then manufactured using four different types of additives (corn oil, citric acid, glycerol, and d-xylose) and ultimately, they were stored in two different conditions prior being tested. In general, manufacturing pellets that were entirely made of lignin generated samples with an overall higher hydrophobicity and higher calorific value. However, the ash and sulfur content of the lignin pellets (1.58% and 0.32% in scenario 2, respectively) were slightly higher than the expected CANplus certification values for Grade A pellets of ≤0.7%, and ≤0.04%, respectively. This study intends to show that lignin could be used to produce this new kind of pellets, pending that the initial material has a low ash and moisture content.

Elucidating the effect of different desorbents on naphthalene desorption and degradation: Performance and kinetics investigation

In this work, the effect of different desorbents (low molecular weight organic acids (LMWOAs), surfactants, and inorganic salts) on naphthalene (NAP) desorption in soil was investigated, and the results showed that NAP desorption pattern fitted the pseudo-second-order kinetics. The addition of LMWOAs, especially citric acid (CA), could stimulate the reactive oxygen species (ROS) generation and NAP degradation in Fe(II) activated persulfate (PS) system, while the presence of surfactants and CaCl2 could inhibit the NAP removal due to the competitive consumption of ROS. The maximum removal of NAP was 97.5% within 120 min at the PS/Fe(II)/CA/NAP molar ratio of 15/5/1/1, and the pseudo-first-order kinetic constant of NAP removal increased from 0.0110 min−1 to 0.0783 min−1 with the addition of CA. Compared with surfactants and inorganic salts, LMWOAs, especially CA, were more suitable as desorbent in soil washing coupled with in situ chemical oxidation technique. Moreover, 1.86 mg L−1 desorbed amount and 36.1% removal of NAP from soil could be obtained with the presence of 1 mM CA. Finally, the significant removal of NAP and other contaminants (phenanthrene, fluoranthene, and benzene series) in actual groundwater could provide theoretical basis and technical support for the remediation of organic contaminated sites with desorbents.

FORMATION OF A FOAMY STRUCTURE OF CONFECTIONERY PASTILLE PRODUCTS

In this paper, the questions of the foamy structure formation in zephyr are considered. Regularities of the influence of recipe components on the foam structure are revealed. The effect of egg white, pectin, white sugar, applesauce and other recipe components on the physicochemical and rheological properties of the foam mass used to produce zephyr has been studied. The addition of pectin leads to an increase in the elastic-plastic properties of the foam mass, and the addition of white sugar leads to an increase in its foaming ability. Recipe components form the foamy structure of the zephyr. The choice of apple pectin allows one to control the density of the zephyr mass and the water activity of the foamy masses. When 0.075% apple pectin is added to a 1% egg white solution, the foaming ability decreases from 190% to 104%, and the foam stability remains practically unchanged. The addition of applesauce, syrup, citric acid and other recipe components to such a foamy mass leads to a slight decrease in the foaming ability, while its stability increases significantly up to 80%, i. e., almost twice. The resulting foamy structure of the zephyr mass is characterized by high physicochemical, organoleptic and rheological parameters, which makes it possible to obtain high quality confectionery products of a given shape.

Preparation of flexible and UV-blocking films from lignin-containing cellulose incorporated with tea polyphenol/citric acid

Lignin-containing bamboo cellulose, fractionated from a pilot-scale microwave liquefaction of bamboo was dissolved in tetrabutylammonium acetate/dimethyl sulfoxide (TBAA/DMSO) for the fabrication of highly flexible, transparent and UV-blocking films. Tea polyphenol (TP) or citric acid (CA) was added during the dissolving process in order to modify the film's properties. The results showed that the addition of TP obviously improved the elongation at break (triple that of the control) and UV-blocking ability of the films. Both the addition of TP and CA could increase the water contact angle of the films. The films incorporated with TP and CA were much more thermal stable than previously reported similar films. The proposed film fabrication mechanism revealed that stable hydrogen bonds formed between the lignin-cellulose matrix and TP/CA, resulting in the enhancement on the properties of the films. This present study showed that lignin-containing cellulose with the incorporation of TP/CA had great potential in the preparation of films in place of plastic.

Enhancement of citric acid on low-grade limestone wet desulfurization performance coupled with spray and partial bubble technology

Developing low-grade limestone as absorbents has been recognized as a prerequisite for industrial application of wet flue gas desulfurization (WFGD) due to the serious depletion of high-grade limestone for SO2 capture. In this research, citric acid was utilized as additive in order to improve the SO2 removal efficiency of low-grade limestone. The enhancement of citric acid on desulfurization performance and the effects of citric acid concentration were investigated based on the spray and partial bubble technology. The results show that the addition of citric acid into low-grade limestone slurry can significantly improve the desulfurization efficiency and the optimal blending ratio between citric acid and low-grade limestone was 1:5. The spent absorbents and reacted liquid phase products were analyzed by X-Ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ion chromatography (IC) and inductively coupled plasma luminescence spectrometry (ICP-OES). These characterizations illustrated that the oxidation of SO32− into SO42− ions along with formation of gypsum was inhibited in the presence of citric acid because of its strong reducibility, whereas the reaction between SO2 and SO32− was greatly promoted, leading to the high SO2 removal efficiency. Furthermore, molecular dynamics (MD) calculation was conducted to provide the microscopic information including the self-diffusion and hydration behavior of SO2 and the gas-liquid interface microstructure. These investigations are of significant importance in providing enhancement mechanism of citric acid on low-grade limestone WFGD process.

Migration and Removal of Labile Cadmium Contaminants in Paddy Soils by Electrokinetic Remediation without Changing Soil pH.

Electrokinetic remediation (EKR) is a viable, advanced cleaning strategy that can permanently reduce the toxicity of soil contaminants. However, EKR is prone to causing changes in soil pH. The negative impacts must be minimized if field-scale application is to be realized. In this study, EKR with polarity reversal was used to avoid soil pH polarization and to clean up cadmium (Cd)-contaminated paddy soils. Results showed that Cd desorbed from oxidizable and residual fractions to labile and easily available parts. Soil moisture content above 0.35 g g−1 was conductive to achieving the desirable Cd-migration rate. The exchangeable Cd phase eventually migrated from both ends of that soil compartment towards the intermediate. Moreover, the addition of citric acid at the concentration of 0.1 mol L−1 was an effective enhancement strategy. The methodology enriched Cd contaminants to specific sites. The technology can be used for electrokinetic-assisted phytoremediation during the rice growing period. Hyperaccumulator is planted in the intermediate area to remove the Cd contaminants. On the other hand, Cd removal is achieved in the region close to the electrodes. The present study provides a theoretical basis for in situ remediation. It has a wider significance for field-scale application.

Properties of Fiber Cement Boards Influenced by BSCH (Banana Stem and Corn Husk) Fibers and Citric Acid Addition

At present, the amount of organic wastes including banana stem and corn husk produced from the Philippines is roughly 56 million technical tons. On the other hand, the construction industry demands innovation to some of the construction materials including cement fiber boards (CFB). The objective of this study is to address the increasing volume of organic wastes including banana stem and corn husk (BSCH) by incorporating BSCH fibers in to cement boards. To test whether the boards fabricated with BSCH fibers is a viable option, the study determined the physical and mechanical properties of cement boards reinforced with BSCH fibers added with citric acid. The experimental results obtained from this study showed that the flexural strength of the cement boards reinforced with banana stem and corn husk fibers is higher than the cement boards without fibers. On the other hand, the compressive strength the cement fiber boards increased in 8% fiber reinforcement and gradually decreased as more fibers were added to the mix. Furthermore, the boards with fibers showed effective drilling characteristics. From the tested cement fiber boards, the cement fiber boards with 8% fiber reinforcement showed the most promising results in both physical and mechanical properties of the fiber cement board.

Citric acid enhances clean recycling of Chinese cabbage waste by anaerobic fermentation

The massive yield and putrefactive nature of Chinese cabbage waste inevitably threatens human and environmental health. Here, anaerobic fermentation technology featuring citric acid additions and high-throughput sequencing technology were performed to assist in the clean recycling of Chinese cabbage waste and reveal the related underlying microbiological mechanisms. The results demonstrated that citric acid additions lowered the pH value (3.89 vs. 4.06) and induced a 20.03% reduction in ammonia-N content, a 341.95% increase in acetic acid production and a 24.09% increase in water-soluble carbohydrate content during the anaerobic period. Moreover, high additive concentrations of citric acid (1.11% dry matter) inhibited pH enhancement (4.07 vs. 4.67), organic acid degradation, spoilage microorganism resuscitation, and ammonia-N formation after 9 days of aerobic exposure. Microbiologically, a 4.06%–10.46% increase in Lactobacillus abundance, 44.06%–84.10% decrease in Leuconostoc abundance and 55.78%–65.86% decrease in Sphingomonas abundance were found in the groups treated with citric acid during the anaerobic period. Moreover, high additive concentrations of citric acid (1.11% dry matter) reduced Naumovozyma and Lactobacillus abundances during aerobic exposure, which were the spoilage-induced microbes indicated by redundancy analysis. In addition, a shift in microbiome equilibrium and a small, simple and competition-enhanced microbiome were induced by citric acid addition, indicating the important role of the interactions between the microbes. Collectively, the present study suggested that citric acid addition at a concentration of 1.11% dry matter improves the clean recycling of Chinese cabbage waste, and the effect of citric acid on aerobic stability is dependent on the concentration, which is linked to variations in the microbiome.

Mechanism of trichloroethylene degradation in Fe(II)-activated peroxymonosulfate coupled with citric acid system in the presence of surfactants.

This study demonstrated that peroxymonosulfate (PMS) activated by Fe(II)/citric acid (CA) could effectively degrade trichloroethylene (TCE) in the presence of Tween-80 (TW-80) or sodium dodecyl sulfate (SDS). Significant TCE removal of 91.6% (90.1%) with 1.3g L-1 TW-80 (2.3g L-1 SDS) were achieved at the PMS/Fe(II)/CA/TCE molar ratio of 4/4/4/1 (20/20/20/1). TCE degradation could be greatly elevated by Fe(II) and CA addition, while the existence of surfactants restrained TCE removal and the inhibitory effect increased with the higher surfactant concentration. The tests of the electron paramagnetic resonance (EPR) and reactive radicals scavenging experiments proved that sulfate radical (SO4-•), hydroxyl radical (HO•), and superoxide radical (O2-•) were responsible for TCE degradation and SO4-• acted as the major one. The influences of initial solution pH and inorganic anions k(Cl- and HCO3-) on TCE removal were also investigated. Eventually, TCE removal in actual groundwater tests with surfactants confirmed that the PMS/Fe(II)/CA process has a huge potential of practical application in remediating the groundwater contaminated by TCE after the pretreatment by solubilization using surfactants.

Effect of the Time of Herbicide Application and the Properties of the Spray Solution on the Efficacy of Weed Control in Maize (Zea mays L.) Cultivation

A field experiment was carried out in 2019–2021. The effect of an increased amount of iron in water and the addition of citric acid on the efficacy of herbicides applied in maize cultivation at various times was tested. In the pre-emergence treatment, thiencarbazone-methyl + isoxaflutole were applied, while in the post-emergence treatment, nicosulfuron + tritosulfuron + dicamba were applied once in a full dose or in low dose system at two times in half of the recommended dose with the addition of an adjuvant. In selected combinations, FeSO4 × 7H2O and citric acid were added to the composition of the spray solution. The species composition of weeds and the efficacy of the herbicides used were determined. Plant stress caused by competition from weeds was investigated by measuring the plant chlorophyll fluorescence. The height of the cultivated plants and their yield level were also determined. The lowest efficacy of weed control was observed when the post-emergence herbicides were applied once. Increasing the iron content in water reduced the efficacy of the herbicides, but the addition of citric acid made it possible to decrease this problem.

Fabrication and characterization of a magnetic biocomposite of magnetite nanoparticles and reduced graphene oxide for biomedical applications

Functionalization of magnetite (Fe3O4) nanoparticles with reduced graphene oxide (rGO) with the preserved magnetic properties of the former presents great potential for applying the Fe3O4/rGO biocomposite in various biomedical applications, such as magnetic resonance imaging, as a therapeutic component in initiating tumour cell death in magnetic and photon ablation therapy, and as an effective carrier for drug delivery. In this study, magnetite nanoparticles (MNPs) with a high saturation magnetization were synthesized by co-precipitation under various conditions, followed by covalent functionalization with citric acid (CA) and subsequent attachment to rGO sheets by physical adsorption. Extensive characterization revealed increasing phase purity with a subsequent decrease in the crystallite size and average size of the MNPs synthesized in an inert atmosphere compared to ambient conditions. Meanwhile, further functionalization of the MNPs with CA by covalent binding does not affect the MNP structure and size, but decreases their agglomeration. To study the magnetic properties of the MNPs and the Fe3O4/rGO composite, magnetization curves were obtained with a vibrating sample magnetometer at a pulsed magnetic field of up to 6.5 kOe. The largest values of saturation magnetization are revealed for the samples synthesized without the addition of CA in an inert atmosphere (σs=80.27 emu/g). The addition of CA to the synthesized MNPs and Fe3O4/rGO composites reduced agglomeration, with σs values in the range from 64.10 to 60.97 emu/g. In vitro biological experiments revealed the MNP concentrations that did not cause any toxic effects on cells for use as magnetic fillers to investigate the strain-mediated effects of hybrid polymer composites on cellular behaviour due to external magnetic field exposure in the next stages of research.

Transfer of MS2 bacteriophage from surfaces to raspberry and pitanga fruits and virus survival in response to sanitization, frozen storage and preservation technologies.

This study assessed the norovirus (NoV) surrogate bacteriophage MS2 transfer from stainless steel, glass and low-density polypropylene surfaces to raspberry and pitanga fruits. The effect of sodium hypochlorite (100 ppm, 1 min) on MS2 survival on whole fruits, the MS2 survival in sanitized fruits and derived pulps during frozen storage, and in response to preservation technologies (heat, organic acids and salts) was also assessed. The highest (p < 0.05) viral transfer (%) was observed from glass and stainless steel (∼90%) to raspberry, and from glass and polypropylene (∼75%) to pitanga, after 60 min of contact. Sodium hypochlorite reduced (p < 0.05) MS2 titer by 3.5 and 3.8 log PFU/g in raspberry and pitanga, respectively. MS2 decreased (p < 0.05) up to 1.4 log PFU/g in frozen stored sanitized fruits (whole fruits and pulps) after 15 days, with no further changes after 30 days. Thermal treatments reduced MS2 titer (p < 0.05) in both fruit pulps. MS2 inactivation was higher in pitanga pulp. The addition of ascorbic acid, citric acid, sodium benzoate, or sodium metabisulfite had little effect (<1 log PFU/g) on MS2 concentration in either fruit. These results may inform NoV risk management practice in processing and handling of fruits.

Infrared Spectroscopic Evidence of WS2 Morphology Change With Citric Acid Addition and Sulfidation Temperature

MS2 morphology is strongly influenced by several parameters including the addition of a chelating agent and sulfidation temperature. In this work, we report the use of citric acid as chelating agent in order to prepare a series of WS2/Al2O3 catalysts that were submitted to sulfidation at several temperatures. The effect of these two parameters in the morphology of the slabs was explored by means of CO adsorption at low temperature followed by IR spectroscopy (IR/CO) and later confirmed by High-Resolution Scanning Transmission Electron Microscopy coupled with High Angular Annular Dark Field detector (HR STEM - HAADF). This allowed to depict the morphology of WS2 slabs by means of calculating the M-edge/S-edge site ratio. The use of citric acid in the preparation stage favors the increase of S-edge site concentration whereas it keeps that of M-edge sites: according to IR/CO, with an increasing amount of citric acid, the WS2 morphology progressively changes from a slightly truncated triangle exhibiting predominantly M edges to a hexagon with both M edge and S edge. In addition, HR STEM-HAADF demonstrated that the addition of citric acid in the impregnation step of W catalysts considerably reduces the size of WS2 nanoparticles increasing their dispersion degree. The morphology of the WS2 plates on the activated WS2/Al2O3 catalyst with a typical sulfidation temperature range (573–673 K) was detected to be a truncated triangle exposing both the M-edge and the S-edge. Furthermore, the IR/CO results indicate that the degree of truncation (ratio of S-edge/M-edge) of WS2 slabs gradually rises with the increasing sulfidation temperature. However, the most determining factor for a modification of the morphology of the slabs turns out to be the presence of citric acid as a chelating agent and not the sulfidation temperature. This change in morphology (i.e., change of S-edge/M-edge ratio) is a key factor for catalytic performance, since the M-edge and the S-edge show different reactivity in hydrodesulfurization (HDS) reactions. Notably, it was also found that the addition of citric acid not only improves the catalytic activity but also the stability of the catalysts, giving the best performance in concentrations higher than (CA/W = 1).

Feasible fabrication of highly dispersed La2O3 promoted MgO composites for CO2 capture at mid-temperature

Homogeneously mixed La2O3–MgO composites were successfully fabricated by spray pyrolysis-post calcination method with the addition of citric acid in the precursor solution and applied on carbon dioxide capture at medium temperature. The additions of citric acid and La component are the key factor for the formation of composite oxides with abundant pores and large surface area. Due to the promoting effect of La2O3 addition on microstructure and physicochemical features, La2O3–MgO composites show excellent CO2 adsorption performance. Typically, the composite with 15 wt% La2O3 exhibits a relatively high CO2 capacity of 26 mgCO2/gadsorbent and high cyclic stability. The superior adsorption performance is attributed to large surface area, special hollow cracked morphology with abundant pores and high concentration of active oxygen vacancy. Furthermore, it is found that the formation of carbonate layers do not shelter the pores of thin shell in hollow microspheres, which provide a flexible framework, support hollow structure integrate and thus sustain repeated regeneration. As a result, the CO2 diffusion is accelerated via the abundant pores from inside or outside of hollow structure. Meaningfully, this flexible structure is endowed with outstanding thermal stability which provides a promising strategy for other materials with fragile structure applied on high temperature reactions.

Electrospun Polyacrylonitrile Nanofibers Mixed with Citric Acid as a Quartz Crystal Microbalance Ammonia Vapor Sensor

AbstractThe detection of ammonia vapor in the air is always challenging and in great demand, with the main issues are their low sensitivity. In this contribution, we developed a quartz crystal microbalance (QCM) gas sensor to detect ammonia vapor in the air using electrospun polyacrylonitrile (PAN) nanofiber mixed with citric acid (CA) as its sensing material. The nanostructured morphology of the as‐prepared nanofiber sensors was confirmed using scanning electron microscopy (SEM), while the existence of the CA in the PAN/CA nanofiber confirms using Fourier transform infrared (FTIR) spectroscopy. The average diameter of the PAN and PAN/CA nanofiber sample was found in the range of 260 nm to 307 nm. The highest sensor sensitivity was obtained by the PAN/CA4 nanofiber sensor with the value of 0.28 Hz/ppm, increasing almost 4 times compared to the unmodified PAN nanofiber sensor (0.075 Hz/ppm). Moreover, the sensor also shows good reversibility, fast response/recovery time, and excellent repeatability sensing performance. The addition of CA into the PAN nanofiber structures enhances the sensor sensitivity, probably due to the enrichment of carboxyl group at the sensor surface. This work could become a promising and alternative way to enhance the sensitivity of a QCM gas sensor modified with polymers doped with suitable compounds.

Phytoremediation of Lead Contaminated Land Using Vetiver zizanoides and Citric Acid as Chelating Agent

Environmental pollution due to hazardous waste in Karangdawa, Margasari, Tegal has an impact on soil and groundwater quality. Lead found in the soil exceeds the permissible standards. It is necessary to recover soil from Lead because it can enter food crops and accumulate in the human body. Phytoremediation is commonly used in land remediation because it’s economical and doesn’t cause secondary environmental problems. One of the ways to optimize Phytoremediation is by using chelating agents. The purpose of the study was to analyze the ability of Vetiver zizanoides and analyze the most optimum dose variation of Citric acid to uptake Lead to the plant. The ability of Vetiver zizanoides and Citric acid as metal chelators in Pb uptake was investigated for 28 days with Citric acid doses of 0.5 g/kg, 1 g/kg, and 2 g/kg. Analysis of Lead concentration in roots, stems, and soil using AAS. From the results of the study, Vetiver zizanoides was able to survive from Lead exposure up to 4979.8 ppm. Application 1 g/kg of Citric acid in the soil, increased the bioconcentration, and bioaccumulation compared to control plants. The results indicated that the addition of Citric acid as a chelating agent could increase the function of Vetiver zizanoides as a phytoremediation agent.